<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<script>
window.onload=function()
{
	var oBtn1=document.getElementById('btn1');
	var oBtn2=document.getElementById('btn2');
	var oBtn3=document.getElementById('btn3');
	 var oDiv=document.getElementById('div1');
	var aCh=oDiv.getElementsByTagName('input');

    //全选
    oBtn1.onclick=function()
	{
		for(i=0;i<aCh.length;i++)
		
	      {aCh[i].checked=true;
		     };
	
	};
	//不选
	  oBtn3.onclick=function()
	{
		for(i=0;i<aCh.length;i++)
	      {
			 aCh[i].checked=false;
			 };
	};
	//反选
		  oBtn2.onclick=function()
	{
		for(i=0;i<aCh.length;i++)
	      {
			  if (aCh[i].checked==true)
			     {  
				   aCh[i].checked=false;
		         }
				 else
				 {
					 aCh[i].checked=true;
				 }
			 };
	};


};
</script>
</head>

<body>
<input id="btn1" type="button" value="全选" />
<input id="btn2" type="button" value="反选" />
<input id="btn3" type="button" value="不选" /><br />
<div id="div1">
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
    <input type="checkbox" /><br />
</div>
</body>

</html>
